Recently, wind turbines have received increased attention as environmentally safe and relatively inexpensive alternative energy sources. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient.
Generally, a wind turbine includes a rotor having multiple blades. The rotor is mounted to a housing or nacelle, which is positioned on top of a truss or tubular tower. Utility grade wind turbines (i.e., wind turbines designed to provide electrical power to a utility grid) can have large rotors (e.g., 30 or more meters in length). In addition, the wind turbines are typically mounted on towers that are at least 60 meters in height. Blades on these rotors transform wind energy into a rotational torque or force that drives one or more generators that may be rotationally coupled to the rotor through a gearbox. The gearbox steps up the inherently low rotational speed of the turbine rotor for the generator to efficiently convert mechanical energy to electrical energy, which is fed into a utility grid.
Wind turbine blades have continually increased in size in order to increase energy capture. It is important to optimize the operation of the wind turbine, including blade energy capture, to reduce the cost of the energy produced. Pitch setting of the blades (i.e., the angle of attack of the airfoil shaped blade), provides one of the parameters utilized in wind turbine control. Typically, controllers are configured to adjust rotor speed (i.e., the rotational speed of the hub around which the blades rotate) and/or power output by adjusting the blade pitch or generator torque in a manner that provides increased or decreased energy transfer from the wind, which accordingly is expected to adjust the rotor speed.
Wind turbines with sophisticated control systems maintain constant tip ratio speed (at low wind speed) or power (at high wind speed) by active torque and blade pitch control. Power production for a wind turbine is negatively impacted if the blades of the wind turbine operate in a non-optimal state. A common problem that causes sub-optimal performance of the machine is blade fouling. Blade fouling may result from a variety of sources. For example, insects, dirt or other debris may accumulate on the leading edge or other surfaces of the turbine blades. The buildup of debris may possibly reduce the efficiency of energy transfer from the wind and may possibly in certain circumstances ultimately result in an aerodynamic stall from separation in airflow over the surface of the wing, and loss of efficiencies. To combat the problem of blade fouling, regular maintenance, including removal and cleaning of the blades, has been required. In addition, certain attempts to combat blade fouling have included complicated and expensive equipment arranged to clean the blades in place.
Therefore, what is needed is a method for cleaning fouled wind turbine blades that does not require expensive and complicated equipment, and does not require removal of the blade or complete shutdown of the wind turbine.